Field of the Invention
The present invention relates to an information processing apparatus, an information processing method, and a computer readable storage medium used for ophthalmologic diagnosis.
Description of the Related Art
To early diagnose life-style related diseases or diseases highly ranked as causes of blindness, eye examinations are widely conducted. As an ophthalmologic apparatus using the principle of a confocal scanning microscope, a Scanning Laser Ophthalmoscope (SLO) is known. The scanning laser ophthalmoscope raster-scans a laser beam serving as measurement light on a fundus, and quickly obtains a high-resolution planar image based on the intensity of return light. An apparatus for capturing such a planar image will be referred to as an SLO apparatus, and a captured planar image as an SLO image hereafter.
Recently, the SLO apparatus can obtain an SLO retinal image having an improved horizontal resolution by increasing the beam diameter of measurement light. However, as the beam diameter of measurement light increases, the S/N ratio and resolution of an SLO image decrease as a result of aberrations in the eye that is the subject of the examination. This results in a problem in obtaining an SLO retinal image. To solve this problem, an adaptive optics SLO apparatus has been developed, which includes an adaptive optics system configured to measure an aberration in an eye to be examined using a wave front sensor in real time and to correct an aberration of measurement light, or its return light, which takes place in the eye to be examined using a wave front correction device. This makes it possible to obtain an SLO image having a high horizontal resolution.
Such an SLO image having a high horizontal resolution can be obtained as a moving image. Various kinds of biological information can be measured using the moving image. For example, to noninvasively observe hemodynamics, a blood vessel of a retina is extracted from each frame, and the moving speed of blood cells in the capillary vessel, and the like, are measured. To evaluate the association with the visual performance using an SLO image, visual cells P are detected, and the density distribution or arrangement of the visual cells P is measured.
In fact, the viewing angle of one SLO image having a high horizontal resolution that the adaptive optics SLO apparatus can capture is typically small. For this reason, when the image capture target region is larger than the viewing angle of the SLO image having a high horizontal resolution, how to set an image capture region in the image capture target region becomes a problem. This will be described with reference to FIGS. 7A to 7G. FIG. 7A is a view schematically showing the section of an eye to be examined. FIGS. 7B to 7G are views showing examples of an SLO image or an image capture target region.
FIG. 7B is a view showing an example of an SLO image having a high horizontal resolution. In FIG. 7B, the visual cells P, a low-luminance region Q corresponding to the position of a capillary vessel, and a high-luminance region W corresponding to the position of a white blood cell are observed. To observe the visual cells P or to measure the distribution of the visual cells P, an SLO image as shown in FIG. 7B is captured by setting the focus position near an extraretinal layer (B5 in FIG. 7A).
On the other hand, blood vessels of the retina and branched capillary vessels run through intraretinal layers (B2 to B4 in FIG. 7A). Especially, in a diseased eye, the image capture target region is often larger than the viewing angle of one SLO image that the SLO apparatus can capture. FIGS. 7C and 7D show examples in which the image capture target region is larger than the viewing angle of an SLO image. FIG. 7C shows an example of the favorite site of a capillary vessel lesion (annular region surrounded by the broken line). FIG. 7D shows an example of a wide visual cell deficiency region (closed black region). In cases as shown in FIGS. 7C and 7D, if all image capture target regions are obtained under a high magnification, setting image capture conditions for many SLO images may be cumbersome, or an increase in the image capture time may make the burden heavy for the subject. The image capture target region includes both regions of great need to capture high-magnification images for diagnosis, and those of little need. It is, therefore, necessary to appropriately set image capture regions such that all regions where it is needed to obtain high-magnification images can be captured in an examination time that does not put a burden upon a subject.
In association with this, an arrangement that captures a plurality of adaptive optics SLO images by changing the image capture position and displays them as a panoramic image is described in Japanese Patent Laid-Open No. 2012-213513 as a technique concerning parameter setting for obtaining a plurality of high-magnification images.
However, when cells, tissues, or lesion regions to be observed or measured specifically distribute wider than a region covered by an image (high-magnification image DH) having a high horizontal resolution, the conventional arrangement has the following problems in efficiently capturing the region of the cells, or the like:
(i) the operator needs to individually designate the values of obtaining parameters (for example, obtaining position, viewing angle, pixel size, number of frames, and frame rate) of a plurality of high-magnification images DHj, inhibiting efficiently obtaining a plurality of images; and
(ii) when an observation target region wider than the high-magnification image DH is captured using the same high-magnification image obtaining parameters, the number of high-magnification images (total number of frames) is enormous (several thousands to several tens of thousands), and it is, therefore, difficult to efficiently obtain the images.
In the arrangement of Japanese Patent Laid-Open No. 2012-213513 as well, the obtaining parameters of a number of high-magnification images are manually determined for each image. The operator is forced to perform cumbersome operations for setting the obtaining parameters.